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I have a White-Rogers 1F82-54 Programmable Thermostat attached to a YORK Olympian 14 (14 SEER & 9 HSPF) & Chromolax HAF-324D (24kw/81900btuh) electric Furnace.
I have been having strange behaviour lately with the programming. It would appear that it is unable (lately) to bring the temp. back up to (23C/73F) from the setback temp (21C/70F) during the night. This only happens when the outside temp is at a certain amount.

When in normal HEAT mode and the temp hovers above or around 0C(32F) +/- 5C(9F), It is OK. Once the temp is around -10C(14F) +/- 5(9F) then it can take forever to come up. Below -15C(5F) (obviously) the furnace only runs. When it's furnace only then all is OK.

This past weekend is a prime example. I purposely backed up the startpoint 2 weeks ago after it started acting up, to 4:30 AM to ask it to go from 21 to 23. By 7AM it was still showing 21C(70F). It was -11C(12.2F) Sunday AM. I gave up and put it to emergency to bring it up. Once up I put it back to normal heat.

If I understand the thermostat owners manual, it moves the startpoint so that the temp. (some sort of smart technology) will be at the requested value at the designated time. If it misses it keeps adjusting until it hits it.

If I assume that most times it kicks in ~30 min.
prior (per the manual) to setpoint my system therefore ran 2.5+ hrs.? Does not the thermostat have a logic built in so that after a certain time, it gives up trying and the
furnace kicks in? I believe it does because I have noticed it do it. Could this "decision-making" circuit be faulty?

By-The-Way: I live in Montreal Canada. It gets cold here in the winter, as you can see by the temperatures I am describing above.

I have been to my local Home-Depot and saw HONYWELL (RTH8500D)replacmeent thermostats. If it's only that I would change it myself, instead of calling service, and be charged double. They (thermostats) appear simple to change.

Diagnostics already done:
=====================================

+ the filter is cleaned religiously every 30 days. I have a
electrostatic filter, so no airflow blockage.

+ I put my hand on the large copper tube (near the furnace) leading from the heat pump to the furnace. I cannot keep my hand on it from the heat, so the heatpump is definitely OK.

+ With the thermostat set to "emergency" it works like a charm. The furnace is therefore OK.

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Just as added information the house was built in 1967 so the R-value of the house is a big question. I have been fighting with the idea of fluctuating the temp. or keeping it steady (because of the low insulation). By the way the heat pump was installed in 2000, the furnace in 1976.

The electric furnace is a 24Kw furnace. My house (30x40 semi-detached duplex) is 2 floors of 1200sq.ft. The lower (basement) has 400 sq.ft. (in-house) as garage. The garage is downhill into the basement level. That means that 1200 (top) + 800 (basement). The basement is finished by the way. The garage is heated independently but set low.

============

As an aside question !

(1) I have read different opinions about programmable thermostats and that they are not good for heatpump systems and should be left at a fixed temp.

Comments ?

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Any idea why this is happening ? Is it worth it to change the thermostat? This would be the 2nd WR brand I change in 4 years. I am tempted to get a HONEYWELL instead.

I got kind of lost on what the problem is? And if you have decided to replace it any way.

Can you simplifiy your question, e.g. The thermostat wont hold the set temperture.

In general replaecing a thremostate is simple if you are reasonable handy and under stand a few things.

The adaptive or intelegent system you describe is where the thermostat learns how long it takes to heat up your house over a several day period. It then keeps track of that time and subtracts if from your target temperture time.

And yes it could be something related to that but we need to go through a few othe steps first.

Sorry for the verbal diarhea! I tried to do a brain dump of everything. OK here we go...

The temp. won't come back up in the AM from a overnight setback. The setback works when its above or at the freezing mark +/- 5C. When it's very cold (i.e. -15C +/- 5C) then it's also OK since only the furnace runs. It's when the outside temp. is around the -10C +/- 5C that things go strange (trying to use both systems). I ask it to go from 21C to 23C at 4:30AM. At 6:30AM it's still 21C. I am obliged to put it in EMERGENCY mode to bring it up, then back to HEAT. Pretty stupid if you ask me. That is why I have put on "HOLD" lateley. If it's the thermostat it's the second thermostat in 4 years (since the HP was installed).

1) In "emergency" mode the setback is OK since only furnace works.

2) If I put the thermostat in "HOLD" (at 23C for example) it's OK. Mind you, I have seen the temp. mometarily drop to 22C on occasions but it's rare.

As I mentioned earlier, I suspected the Heat Pump but if I place my hand on the large copper tube it is VERY hot to the touch, so it appears OK. My HP is a monster. I purposely bought one to avoid short-cycling from my furnace since I was getting cold rooms in the house.

FYI: As I mentioned I have a 2 story house. The basement is finished with about 30% being eaten up by my in-house garage. I also have a slow-combustion wood-stove in the basement playroom that we run kinda steady to keep the basement a little more cosy. Can I assume that because we run this thing it is messing with the thermostat's "intelligence"? The thermostat is on the main floor away from stairwell BUT some heat does trickle up. Just a thought!

To answer your questions:

1) About the purchase, No, I have not bought one yet. I went to local reno stores. Only 2 HONEYWELL models exist (CT3611 & RTH8500D). I am kinda partial to the second. Looks very user-friendly. I am torn between calling in the HVAC guy (HP installer) or putting in a thermostat myself.

DILEMMA: If I put one in myself and it's not it I blew the $$$ for a thermostat. If I call him in and he tells me I need a Thermostat then he will no-doubt charge me more because he has to install it. I agree with you, installing a thermostat, even an HP model, appears easy (i.e. 5 wires)

It sounds like the thermostat is just being a little too stingy about providing auxiliary heat.

When it's giving you this trouble, does the thermostat indicate that it's calling for auxilary heat? Try doing a manual override and boosting the setpoint up to 24 or 25 (without switching to Emergency Heat). If the aux heat was off, then turns on when you boost the setpoint and warms up the house promptly, that'll confirm my hunch.

Does the thermostat do half-degrees in Celcius mode, or only whole degrees?

I'd say get a pro. He can get you a much better thermostat than you can buy at retail. Looks can be deceiving, but what Honeywell sells at Home Depot (etc.) is stripped down compared to what's available to the pros.

Right now, you probably don't have an outside temp sensor for the thermostat, just an "outdoor thermostat". Its function is to disable the heat pump in super-cold conditions and make the system rely on electric heat only. Well, imagine yourself in the thermostat's shoes... sometimes you call for heat and you get a prompt response (because you get 24 kW of electric heat)... other times you get almost no response for ages. It makes it hard for it to know what to expect when it goes to recover from a setback- and is probably best optimized for more moderate climates, where they avoid electric heat like the plague. In Quebec, though, it comes with the territory. With adaptive response, though, it can't know how to adapt when it gets vastly different output from the heating equipment from one day to the next.

I would say you'll get the best results in those weather conditions with a nice Honeywell thermostat, equipped with an outdoor temperature sensor, and *without* the outdoor thermostat you probably have now. With this setup, the thermostat can be configured to make the decision as to whether it's too cold to run the heat pump or not. This way, before it tries to recover from a setback, it knows what kind of output, if any, to expect from the heat pump. It gives it enough information to be able to adapt correctly. You'll definitely want to get a pro to implement a setup like this, though; there's more involved than a basic thermostat swap.

When in normal HEAT mode and the temp hovers above or around 0C(32F) +/- 5C(9F), It is OK. Once the temp is around -10C(14F) +/- 5(9F) then it can take forever to come up. Below -15C(5F) (obviously) the furnace only runs. When it's furnace only then all is OK.

Just as added information the house was built in 1967 so the R-value of the house is a big question. I have been fighting with the idea of fluctuating the temp. or keeping it steady (because of the low insulation). By the way the heat pump was installed in 2000, the furnace in 1976.

Any idea why this is happening ? Is it worth it to change the thermostat? This would be the 2nd WR brand I change in 4 years. I am tempted to get a HONEYWELL instead.

I confess... I didn't read the whole post...
I got ancy and wanted to give my reply on the matter...

When the temp is cold enough to cause probs... have a tech come out and make sure all the heaters are coming on.

Man thats cold...
I'm too lazy to do a load calc for ya hehe
Its possible your just getting down to the temp where the heating unit is just able to match your heat loss.
Meaning it will be able to 'maintain' a setpoint.. but have one heck of a time recovering.

i.e.
Imagine your house as a five gallon bucket
Poke a hole in the bottom of the bucket
Fill it up with water ( = heat)
Water drips out of the hole( = heat loss)
Poor water in every once in a while to keep the water level fairly constant. ( = Heater turning on to maintain house temp)

Lets say you are able to poor in two cups per minute
The bucket is losing one cup per minute
You can keep up no prob

The AUX kicks in almost instantaneously and stays on at the -10C outside. I would imagine at -10C there isn't much heat to around. The heat is not HOT coming out. I am guessing it is using the first, maybe second, bank(s). I have 4-5 banks in the furnace, not sure.

As for 1/2 degress, nope, the t-stat only does full degree changes. I can always switch to F (1C=1.8F) if that answers your question.

WORMY:
======

Love your bucket analogy. You should be a teacher. I understood your explanation exactly (I am not being sarcastic).

BEENTHERE:
==========

I do not believe I can "shut off" the intelligent function. As far as I remember from the t-stat manual I must unscrew the t-stat from the wall and snip a wire to "permamently" shut off the functionality. I am not too comfortable doing that, in case I have to go back.

CONCLUSION............
=======================

If I understand all this I therefore conclude that I should NOT yo-yo the temp. Set it and forget it where a HP is concerned. As for my current t-stat, it does not have a sensor outside. I know there is a metalic "bulb" on the side of the HP. I would imagine it's for the HP to decide to cut out when the temp. is cold. What I did notice from the wiring though is a "monitor" wire on the t-stat. I assume a signal is sent to the t-stat from the HP. I guess not !

Further fuel for the fire. I have been trying to increase house efficiency slowly over the last little while. This summer's push was to weatherproof the house (weather strip, windows, doors, caulking, etc.) As such, I started getting complaints from the family on dryness in the house. Got a proper %RH meter for the house. Turns out the best I could do on a good day (above freezing was 32%). In full cold mode, and furnace blasting, it sinks to 23%)...Yah I know...OUCH!.

Am in the process of adding a furnace humidifier. It was yanked off when the HP was installed since nobody complained. Since the house was old (late 60's) I assumed that it (moisture) was coming in anyway. Now the house is tight-er. I just created another problem. Am now figuring, with humidifier, that I can bump down the temp. since the humidity will help. May help!

As for the t-stat, I have read, from HONEYWELL, and from another thread, that the VisionPRO line is the way to go. I read the setup and you can set the aggressiveness of the temp. increase from setback. This may help my situation. It can also accept on outdoor sensor. Answer your recomendations.

I have always read, and experienced, that it is better to have a cooler temp. to sleep. Thus the reasoning for the programmable t-stat.

I used to have the t-stat bring the temp up 1C at a time, with no luck. I was told by a local installer that most programmable t-stats will not kick in the strips for a 1C shift, it usually needs 2C or more. Thereby bumping the temp in the AM by 2C. I was also told NOT to program more than a 5F swing in temp. It will kill any/all savings. So, my programming is such:

As luck would have it, none to be found, at least in the Montreal area. I did the route of all the RENO stores and only models I was able to find were the common "bypass" sponge roller version or the newer metalic "flo-thru" pad type such as (WAIT 5000/6000/7000)

The worst kick in the teeth is that my particular setup does not allow me to place the humidifier in the usual place (on the cold air return next to furnace). The furnace is off the floor, essentially eating up my cold-air return surface.

This trunk then stops because the installer decided to use adjoining floor joists (covered in sheet metal) as a return trunk.

I have seen this setup before. My parent's old house had it since the basement was 6'. Anyway, I came up with 2 solutions:

1) Find a humidifier that mounts under the duct.
2) Build a triangular sheet-metal box that suspends under the duct, to allow attachment a conventional humdiifer to.

Since finding a under-duct model was impossible (even went to SEARS) I opted for solution 2. Am lucky the in-floor duct section runs near enough that the hot-air feed off the supply trunk is close.

BTW: I did find a spray version, but it was not recommended for HP systems, so scratch that idea.

I have seen the steam ones in the US (Google does wonders).

My only concern is since the device would be suspended in the duct where 3 sides are wood, it may create another problem (wood rot, mould, etc..). Speculation here, no solid proof/research! I also read that it is expensive to buy and run.

Have I made the right decision? Time will tell.

Spent the weekend plugging it in. Almost done. I found a version made by THERMOLEC, that has a small pump in the pan (M-400). At timed intervals it dumps some of the water, and hopefully some of the minerals. The claim is that it reduces the mineral buildup on the sponge.